# Finding percentage of one of two variables in an equation composed of three

The title is probably horrible, but I couldn't think of a better sentence to describe what I'm attempting to do. I want to take the result of an equation made with 3 variables and then, with two of the variables, create the same number as if the third variable in the initial equation hadn't existed. Then, I want to find the percentage of each variable in the second equation. Once again, that was probably a terrible explanation, so here's an example.

result = a + b * c


That's the initial equation. Now plugging in numbers:

result = 1+2*3
result = 7


Now I want to be able to take 2 and 3 and make them add up to 7 somehow, then get the percentage of each in 7.

2/7=29%
3/7=43%


As you can see, this doesn't add up to 100%. I need it to add up to 100%, but I have no clue how. If more explanation is needed, just ask.

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Vote to close as not a real question. No responses to the answers provided. – Ross Millikan Jun 11 '11 at 4:53

More explanation is needed. Maybe one way to go is, I put forward a suggestion, you tell me why it's not what you want, that way maybe we get a clearer idea of what you want.

$7=2+2+3$, so the percentages of $2$ and $3$ in $7$ are $66$-and-two-thirds and $33$-and-one-third, respectively.

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I don't understand how you came up with 66% & 33%, can you explain? It seems like what I'm trying to do (find 2 percentages that add up to 100 using) but I don't understand how you did that. Trying 2/(5-2) returns 40%. – Jimmy May 12 '11 at 1:30
I used three numbers, and two out of three of them were $2$s, and one out of three of them was a $3$; so, two-thirds, which is to say, 66-and-two-thirds per cent, were $2$s, etc. But evidently this is not what you wanted, although I'm not sure I understand the answer you've given. – Gerry Myerson May 12 '11 at 6:36

I found what I was looking for. A more compressed formula would be appreciated, though.

$b/(b+c)*100)/100*(a+b*c)$

$c/(b+c)*100)/100*(a+b*c)$

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You've a few unpaired parentheses... – J. M. May 12 '11 at 2:37
So your formula tells you the percentage of $2$s is $2/(5)100/100(7)$. I'm not sure how to parse this and get a number out of it. It's surely not $(2/500)/700=2/350000=1/175000$. Can it be $2/(500/700)$? That's $14/5$, and then the second number is $21/5$, and they don't add up to $100$. So before anyone can give a "more compressed formula," you had better show us how you think your formula works when $a=1$, $b=2$, and $c=3$. – Gerry Myerson May 12 '11 at 6:42
The best I can parse this is to ignore the right parenthesis after the first $100$ and evaluate from left to right. Then the $100$s divide out and we have $\frac{b}{(b+c)(a+b*c)}$ and $\frac{c}{(b+c)(a+b*c)}$. Then $\frac{a}{a+b*c}+\frac{b}{(b+c)(a+b*c)}+\frac{c}{(b+c)(a+b*c)}=1$ but I don't know what to make of it. – Ross Millikan Jun 11 '11 at 4:50